I recently had to buy a spark plug spanner to fit new spark plugs to the Diavel as nothing I had fitted. I found this, https://www.halfords.com/workshop-t...lhShFg9FwVU3B8j7Lsj8217dG5-gusEQaAko8EALw_wcB at Halfords and it does the job. 3/8” drive, thin walled, a foot long and magnetic so you don’t lose the spark plug. Andy
I prefer to follow up with a barely magnetic screwdriver for retrieval, having it precariously hanging and knowing the slightest knock on the cylinder head will send it careering back down. It's like a mechanics version of those electric buzzer games.
That's handy to know, as I've just bought that set so I can butcher the 16mm one to replace my gear-position sensor
